Mercury's Seasonal Sodium Exosphere: MESSENGER Orbital Observations
The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) Ultraviolet and Visible Spectrometer (UVVS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft now orbiting Mercury provides the first close-up look at the planet's sodium exosphere. UV...
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ftnasantrs:oai:casi.ntrs.nasa.gov:20150010117 2023-05-15T18:22:42+02:00 Mercury's Seasonal Sodium Exosphere: MESSENGER Orbital Observations McClintock, William E. Vervack, Ronald J., Jr. Cassidy, Timothy A. Burger, Matthew H. Killen, Rosemary M. Merkel, Aimee W. Sarantos, Menelaos Unclassified, Unlimited, Publicly available November 1, 2014 application/pdf http://hdl.handle.net/2060/20150010117 unknown Document ID: 20150010117 http://hdl.handle.net/2060/20150010117 Copyright, Distribution as joint owner in the copyright CASI Astrophysics GSFC-E-DAA-TN18236 2014 ftnasantrs 2019-07-21T06:10:32Z The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) Ultraviolet and Visible Spectrometer (UVVS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft now orbiting Mercury provides the first close-up look at the planet's sodium exosphere. UVVS has observed the exosphere from orbit almost daily for over 10 Mercury years. In this paper we describe and analyze a subset of these data: altitude profiles taken above the low-latitude dayside and south pole. The observations show spatial and temporal variations, but there are no obvious year-to-year variations in most of the observations. We do not see the episodic variability reported by some ground-based observers. We used these altitude profiles to make estimates of sodium density and temperature. The bulk of the exosphere, at about 1200 K, is much warmer than Mercury's surface. This value is consistent with some ground-based measurements and suggests that photon-stimulated desorption is the primary ejection process. We also observe a tenuous energetic component but do not see evidence of the predicted thermalized (or partially thermalized) sodium near Mercury's surface temperature. Overall we do not see the variable mixture of temperatures predicted by most Monte Carlo models of the exosphere. Other/Unknown Material South pole NASA Technical Reports Server (NTRS) South Pole |
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NASA Technical Reports Server (NTRS) |
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Astrophysics |
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Astrophysics McClintock, William E. Vervack, Ronald J., Jr. Cassidy, Timothy A. Burger, Matthew H. Killen, Rosemary M. Merkel, Aimee W. Sarantos, Menelaos Mercury's Seasonal Sodium Exosphere: MESSENGER Orbital Observations |
topic_facet |
Astrophysics |
description |
The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) Ultraviolet and Visible Spectrometer (UVVS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft now orbiting Mercury provides the first close-up look at the planet's sodium exosphere. UVVS has observed the exosphere from orbit almost daily for over 10 Mercury years. In this paper we describe and analyze a subset of these data: altitude profiles taken above the low-latitude dayside and south pole. The observations show spatial and temporal variations, but there are no obvious year-to-year variations in most of the observations. We do not see the episodic variability reported by some ground-based observers. We used these altitude profiles to make estimates of sodium density and temperature. The bulk of the exosphere, at about 1200 K, is much warmer than Mercury's surface. This value is consistent with some ground-based measurements and suggests that photon-stimulated desorption is the primary ejection process. We also observe a tenuous energetic component but do not see evidence of the predicted thermalized (or partially thermalized) sodium near Mercury's surface temperature. Overall we do not see the variable mixture of temperatures predicted by most Monte Carlo models of the exosphere. |
format |
Other/Unknown Material |
author |
McClintock, William E. Vervack, Ronald J., Jr. Cassidy, Timothy A. Burger, Matthew H. Killen, Rosemary M. Merkel, Aimee W. Sarantos, Menelaos |
author_facet |
McClintock, William E. Vervack, Ronald J., Jr. Cassidy, Timothy A. Burger, Matthew H. Killen, Rosemary M. Merkel, Aimee W. Sarantos, Menelaos |
author_sort |
McClintock, William E. |
title |
Mercury's Seasonal Sodium Exosphere: MESSENGER Orbital Observations |
title_short |
Mercury's Seasonal Sodium Exosphere: MESSENGER Orbital Observations |
title_full |
Mercury's Seasonal Sodium Exosphere: MESSENGER Orbital Observations |
title_fullStr |
Mercury's Seasonal Sodium Exosphere: MESSENGER Orbital Observations |
title_full_unstemmed |
Mercury's Seasonal Sodium Exosphere: MESSENGER Orbital Observations |
title_sort |
mercury's seasonal sodium exosphere: messenger orbital observations |
publishDate |
2014 |
url |
http://hdl.handle.net/2060/20150010117 |
op_coverage |
Unclassified, Unlimited, Publicly available |
geographic |
South Pole |
geographic_facet |
South Pole |
genre |
South pole |
genre_facet |
South pole |
op_source |
CASI |
op_relation |
Document ID: 20150010117 http://hdl.handle.net/2060/20150010117 |
op_rights |
Copyright, Distribution as joint owner in the copyright |
_version_ |
1766202107451408384 |